"I looked and saw ... an African American on the ground with two police officers over top of him," he said. "What I didn't know at the time is that a homeless person called in and said there's a guy threatening me with a gun."

While acknowledging that institutional racism "exists throughout our society," Biden said the way to begin to close this perception gap is fairly straightforward: cops need to be better trained in de-escalation tactics. And they need to know who they're policing, just as citizens need to know who they're being policed by.